Overview
- The peer‑reviewed study by Martin Bauch and Ulf Büntgen, published December 4 in Communications Earth & Environment, links a mid‑1340s volcanic sulfur injection to the pandemic’s start.
- Ice cores from Greenland and Antarctica show a large sulfur spike around 1345, while European tree rings record the coldest run of summers in 1345–1347 since 1257, consistent with eruption‑driven cooling.
- Price records and archives describe crop failures, spiking grain costs, and emergency policies that pushed Venice, Genoa, and others to secure Black Sea grain after easing restrictions with the Golden Horde.
- The authors argue fleas carrying Yersinia pestis could survive on grain dust during long voyages, noting Venice reported first cases less than two months after the last grain ships returned, whereas grain‑self‑sufficient cities like Milan and Rome largely escaped the initial wave.
- The proposed pathway remains probabilistic due to an unidentified volcano and patchy medieval documentation, and the authors highlight broader lessons about how climate shocks interacting with trade can accelerate zoonotic disease spread.